Bronchial hyperresponsiveness in women with chronic obstructive pulmonary disease related to wood smoke

Blood eosinophils levels in a Colombian cohort of biomass-and tobacco-related COPD patients

Introduction

Chronic obstructive pulmonary disease (COPD) is a major cause of illness and death among adults. In 2019, the Global Initiative for Chronic Obstructive Lung Disease (GOLD) strategy incorporated blood eosinophils as a biomarker to identify patients at increased risk of exacerbations which, with the history of exacerbations during the previous year, allows identification of patients who would benefit from anti-inflammatory treatment to reduce the risk of future exacerbations. The aim of this study was to describe demographic and clinical characteristics, eosinophil counts, and exacerbations in a cohort of COPD patients stratified by clinical phenotypes (non-exacerbator, frequent exacerbator, asthma-COPD overlap) in a Colombian cohort at 2600 meters above sea level.

Methods

A descriptive analysis of a historical cohort of patients with a confirmed diagnosis of moderate to severe COPD (FEV1/FVC < 0.7 and at least one risk factor for COPD) from two specialized centers with comprehensive disease management programs was performed from January 2015 to March 2019. Data were extracted from medical records 1 year before and after the index date.

Results

200 patients were included (GOLD B: 156, GOLD E: 44; 2023 GOLD classification); mean age was 77.9 (SD 7.9) years; 48% were women, and 52% had biomass exposure as a COPD risk factor. The mean FEV1/FVC was 53.4% (SD 9.8), with an FEV1 of 52.7% (20.7). No differences were observed between clinical phenotypes in terms of airflow limitation. The geometric mean of absolute blood eosinophils was 197.58 (SD 2.09) cells/μL (range 0 to 3,020). Mean blood eosinophil count was higher in patients with smoking history and frequent exacerbators. At least one moderate and one severe exacerbation occurred in the previous year in 44 and 8% of patients, respectively; during the follow-up year 152 exacerbations were registered, 122 (80%) moderate and 30 (20%) severe. The highest rate of exacerbations in the follow-up year occurred in the subgroup of patients with the frequent exacerbator phenotype and eosinophils ≥300 cells/μL.

Discussion

In this cohort, the frequency of biomass exposure as a risk factor is considerable. High blood eosinophil count was related to smoking, and to the frequent exacerbator phenotype.

Sputum Biomarkers in Wood and Tobacco Smoke Etiotypes of Chronic Obstructive Pulmonary Disease

Introduction

There is a need to better understand the etiotypes of chronic obstructive pulmonary disease (COPD) beyond the tobacco-smoke (TS-COPD). Wood smoke COPD (WS-COPD) is characterized by greater airway compromise, milder emphysema, and slower rate of lung function decline than TS-COPD. However, it is unclear if these two etiotypes of COPD have differences in sputum biomarker concentrations. Objective was to compare sputum levels of selected sputum biomarkers between WS-COPD and TS-COPD, and healthy controls.

Methods

Eighty-eight women (69±12 years) were recruited and classified into: WS-COPD (n=31), TS-COPD (n=29) and controls (n=28). Using ELISA, we determined induced sputum levels of metalloproteinase 9 (MMP-9), chemokine ligand 5 (CCL5), interleukin-8 (IL-8), chemokine ligand 16 (CCL16/HCC-4) and vascular endothelial growth factor (VEGF-1). Differences were analyzed by Kruskal-Wallis and Mann-Whitney-U tests and correlation between airflow limitation and biomarkers by Spearman's test.

Results

At similar degree of airflow obstruction, anthropometrics and medications use, the level of sputum CCL5 was higher in TS-COPD than WS-COPD (p=0.03) without differences in MMP-9, IL-8, CCL16/HCC-4, and VEGF-1. Women with WS-COPD and TS-COPD showed significantly higher sputum levels of MMP-9, IL-8 and CCL5 compared with controls (p<0.001). FEV1% predicted correlated negatively with levels of MMP-9 (rho:-0.26; P=0.016), CCL5 (rho:-0.37; P=0.001), IL-8 (rho:-0.42; P<0.001) and VEGF (rho:-0.22; P=0.04).

Conclusion

While sputum concentrations of MMP-9, IL-8, and CCL5 were higher in COPD women compared with controls, women with TS-COPD had higher levels of CCL5 compared with those with WS-COPD. Whether this finding relates to differences in pathobiological pathways remains to be determined.

The "Slow Horse Racing Effect" on Lung Function in Adult Life in Chronic Obstructive Pulmonary Disease Associated to Biomass Exposure

Although different trajectories in lung function decline have been identified in patients with COPD associated to tobacco exposure (TE-COPD), genetic, environmental, and infectious factors affecting lung function throughout life have not been fully elucidated in patients with COPD associated to biomass (BE-COPD). In this review, we present current epidemiological findings and notable advances in the natural history of lung decline in BE-COPD, as well as conditions modeling the FEV₁ trajectory, such as health insults, during the first years of childhood. Evidence shows that women exposed to biomass smoke reach adult life with a lower FEV₁ than expected. However, in contrast to the “horse racing effect” predicting an excessive lung-function decline in forthcoming years, as observed in smokers, this decline is slower in non-smokers, and no rapid decliners are observed. Accordingly, BE-COPD might be considered another phenotype of COPD based on assessments of lung function decline. Likewise, other functional and clinical aspects described in this review suggest that this condition might be similar to TE-COPD. More research is needed to fully characterize this subgroup of variants of COPD.

Comparison of Chronic Obstructive Pulmonary Diseases Induced by Wood Smoke and Tobacco Smoke

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a progressive airflow limitation and decline in lung function. Although tobacco smoke is the leading risk factor for COPD, air contamination by wood-burning smoke is also of great concern. About half of the world's populations, especially in developing countries such as Iran, exploit this energy source for cooking and heating. It is remained unknown if COPD induced by wood smoke from baking bread (COPD-B) and COPD induced by tobacco smoke (COPD-S) have different symptoms and clinical presentations. To fill this gap, the present study was to describe such differences.

MATERIALS AND METHODS

This retrospective cohort study was performed in Afshar COPD clinics affiliated with the Shahid Sadoughi University of Medical Sciences, Yazd, Iran. The clinical records of 231 patients with the COPD diagnosis were reviewed. After considering inclusion and exclusion criteria, 91 patients (46 with COPD -B and 45 with COPD-S) underwent physical examination and para-clinical assessments (i.e., respiratory function tests, Chest X-ray, and quality of life test).

RESULTS

The COPD-B patients were mainly women at older age and had higher FEV ₁ /FVC and FEF-75; however, they had fewer post-bronchodilator positive responses to FEV ₁ (suggesting a restriction pattern) and sputum production, compared to the COPD-S patients. Regarding the other parameters, there were no statistically significant differences between the two groups.

CONCLUSION

This was the first study evaluating and revealing some differences in the clinical and paraclinical characteristics of the COPD-B patients (with prolonged exposure to wood smoke from bread baking; >100 hours per year, for at least 10 years) and COPD-S patients (>10 packs per year of exposure to tobacco smoke).

Validation of chronic obstructive pulmonary disease severity score (COPDSS) for primary care in a Colombian population

Introducción.

La enfermedad pulmonar obstructiva crónica (EPOC) es un importante problema de salud mundial con una alta morbimortalidad. Se requiere la medición de la gravedad de la enfermedad mediante una herramienta de fácil aplicación, bajo costo y fácil disponibilidad en áreas rurales.

Objetivo.

Evaluar la validez y contabilidad del puntaje de valoración de la gravedad de la EPOC (Chronic Obstructive Pulmonary Disease Severity Score, COPDSS) en una población de atención primaria en Colombia.

Materiales y métodos.

Se hizo un estudio de corte transversal en una muestra de 100 pacientes con diagnóstico de EPOC según las guías GOLD. La validez concurrente se evaluó correlacionando los resultados del COPDSS con otras variables de importancia como las del cuestionario sobre la enfermedad respiratoria crónica (Chronic Respiratory Disease Questionnaire, CRQ) y el volumen espiratorio forzado en el primer segundo (Forced Expiratory Volume in one second, FEV₁).

Resultados.

El COPDSS presentó una correlación significativa con el FEV₁ (r=-0,33), con el CRQ (r=-0,57) y sus dimensiones: disnea (r=0,51), fatiga (r=0,53), función emocional (r=0,43) y control de la enfermedad (r=0,50). En el análisis factorial se determinó un solo factor con una varianza acumulada de 59,1 %. El análisis de coherencia interna mostró un alfa de Cronbach de 0,76, valor este considerado adecuado.

Conclusiones.

Se observó que el uso del COPDSS como cuestionario de valoración de la gravedad de pacientes con EPOC en Colombia tenía validez y confiabilidad adecuadas y que es de fácil aplicación en la atención primaria.

Biomass smoke COPD has less tomographic abnormalities but worse hypoxemia compared with tobacco COPD

Special attention has emerged towards biomass smoke-induced chronic obstructive pulmonary disease (COPD), providing new knowledge for prevention and therapeutic approach of non-smoker COPD patients. However, the understanding of biomass smoke COPD is still limited and somewhat controversial. The aim of the present study was to compare COPD exclusively caused by tobacco smoking with COPD exclusively caused by environmental or occupational exposures. For this cross-sectional study, COPD patients were recruited from outpatient clinics and formed two groups: non-smoker COPD group (n=16) with exposure to biomass smoke who did not smoke cigarette and tobacco smoker COPD group (n=15) with people who did not report biomass smoke exposure. Subjects underwent pulmonary function tests, thoracic high-resolution computed tomography, 6-min walk test, and sputum induction. The non-smoker COPD group had biomass smoke exposure of 133.3±86 hour-years. The tobacco COPD group smoked 48.5±27.4 pack-years. Women were 62.5 and 66.7%, respectively, of non-smokers and smokers. The non-smoker COPD group showed higher prevalence of dyspnea, lower arterial oxygen tension (PaO2), and lower arterial oxygen saturation (SaO2%) with similar spirometry results, lung volumes, and diffusion capacity. Regarding inflammatory biomarkers, differences were detected in sputum number of lymphomononuclear cells and in sputum concentrations of interleukin (IL)-6 and IL-8 with higher values in the smoker group. Emphysema was more prevalent in the tobacco smoker group, which also showed higher relative bronchial wall thickness and lower lung density by quantitative analysis. Biomass smoke induced more hypoxemia compared to tobacco in COPD patients with similar severity.

Risk of acute exacerbations in chronic obstructive pulmonary disease associated with biomass smoke compared with tobacco smoke

BACKGROUND

Risk of exacerbations in chronic obstructive pulmonary disease (COPD) associated with biomass smoke has not been well addressed, although biomass smoke is similar in composition to tobacco smoke.

METHODS

To investigate whether the risk of exacerbations in COPD associated with biomass smoke differs from that in COPD associated with tobacco smoke, we recruited patients with COPD from two Korean multicenter prospective cohorts. In a multiple linear regression model, the standardized regression coefficient (β) of biomass smoke exposure ≥25 years was most similar to that (β') of tobacco smoke exposure ≥10 pack-years (β = - 0.13 and β' = - 0.14). We grouped patients with COPD into four categories based on the above cut-offs: Less Tobacco-Less Biomass, Less Tobacco-More Biomass, More Tobacco-Less Biomass, and More Tobacco-More Biomass. The main outcome was the incidence of moderate or severe exacerbations.

RESULTS

Among 1033 patients with COPD, 107 were included in Less Tobacco-Less Biomass (mean age: 67 years, men: 67%), 40 in Less Tobacco-More Biomass (mean age: 70 years, men: 35%), 631 in More Tobacco-Less Biomass (mean age: 68 years, men: 98%), and 255 in More Tobacco-More Biomass (mean age: 69 years, men: 97%). The incidence rates of exacerbations were not significantly different between Less Tobacco-More Biomass and More Tobacco-Less Biomass (adjusted incidence rate ratio, 1.03; 95% confidence interval, 0.56-1.89; P = 0.921). No interaction between sex and tobacco and biomass smoke was observed. When propensity score matching with available covariates including age and sex was applied, a similar result was observed.

CONCLUSIONS

Patients with COPD associated with biomass smoke and those with COPD associated with tobacco smoke had a similar risk of exacerbations. This suggests that patients with COPD associated with biomass smoke should be treated actively.

Chronic Obstructive Pulmonary Disease in Latin America

The PLATINO and PREPOCOL population-based studies documented the prevalence of chronic obstructive pulmonary disease (COPD) in several Latin American (Mexico City, Sao Paulo, Montevideo, Santiago and Caracas) and Colombian (Medellin, Bogota, Barranquilla, Bucaramanga and Cali) cities. COPD ranged between 6.2 and 19.6% in individuals ≥40 years of age, with substantial rates of underdiagnosis (up to 89%) but also overdiagnosis, mostly due to the lack of spirometric confirmation. The main risk factor was tobacco smoking, but male gender and age were also associated with COPD. COPD in never smokers represented about one third of the cases and was associated with previous history of tuberculosis or a diagnosis of asthma. COPD associated with biomass smoke exposure was a common clinical phenotype in Latin America, found as a risk factor in PREPOCOL and other observational studies in the region. Smoking has been decreasing in Latin America and efforts have been made to implement cleaner biomass stoves. Unfortunately, treatment of COPD in Latin America remains highly variable with low rates of smoking cessation counselling, low use of inhaled bronchodilators and influenza vaccination. A primary-care approach to COPD, particularly in the form of integrated programs is lacking but would be critical to improving rates of diagnosis and treatment of COPD.

ERS/ATS workshop report on respiratory health effects of household air pollution

Exposure to household air pollution (HAP) from solid fuel combustion affects almost half of the world population. Adverse respiratory outcomes such as respiratory infections, impaired lung growth and chronic obstructive pulmonary disease have been linked to HAP exposure. Solid fuel smoke is a heterogeneous mixture of various gases and particulates. Cell culture and animal studies with controlled exposure conditions and genetic homogeneity provide important insights into HAP mechanisms. Impaired bacterial phagocytosis in exposed human alveolar macrophages possibly mediates several HAP-related health effects. Lung pathological findings in HAP-exposed individuals demonstrate greater small airways fibrosis and less emphysema compared with cigarette smokers. Field studies using questionnaires, air pollution monitoring and/or biomarkers are needed to better establish human risks. Some, but not all, studies suggest that improving cookstove efficiency or venting emissions may be associated with reduced respiratory symptoms, lung function decline in women and severe pneumonia in children. Current studies focus on fuel switching, stove technology replacements or upgrades and air filter devices. Several governments have initiated major programmes to accelerate the upgrade from solid fuels to clean fuels, particularly liquid petroleum gas, which provides research opportunities for the respiratory health community.

Review of the health effects of wildland fire smoke on wildland firefighters and the public

Each year, the general public and wildland firefighters in the US are exposed to smoke from wildland fires. As part of an effort to characterize health risks of breathing this smoke, a review of the literature was conducted using five major databases, including PubMed and MEDLINE Web of Knowledge, to identify smoke components that present the highest hazard potential, the mechanisms of toxicity, review epidemiological studies for health effects and identify the current gap in knowledge on the health impacts of wildland fire smoke exposure. Respiratory events measured in time series studies as incidences of disease-caused mortality, hospital admissions, emergency room visits and symptoms in asthma and chronic obstructive pulmonary disease patients are the health effects that are most commonly associated with community level exposure to wildland fire smoke. A few recent studies have also determined associations between acute wildland fire smoke exposure and cardiovascular health end-points. These cardiopulmonary effects were mostly observed in association with ambient air concentrations of fine particulate matter (PM2.5). However, research on the health effects of this mixture is currently limited. The health effects of acute exposures beyond susceptible populations and the effects of chronic exposures experienced by the wildland firefighter are largely unknown. Longitudinal studies of wildland firefighters during and/or after the firefighting career could help elucidate some of the unknown health impacts of cumulative exposure to wildland fire smoke, establish occupational exposure limits and help determine the types of exposure controls that may be applicable to the occupation.

Defining and targeting health disparities in chronic obstructive pulmonary disease

The global burden of chronic obstructive pulmonary disease (COPD) continues to grow in part due to better outcomes in other major diseases and in part because a substantial portion of the worldwide population continues to be exposed to inhalant toxins. However, a disproportionate burden of COPD occurs in people of low socioeconomic status (SES) due to differences in health behaviors, sociopolitical factors, and social and structural environmental exposures. Tobacco use, occupations with exposure to inhalant toxins, and indoor biomass fuel (BF) exposure are more common in low SES populations. Not only does SES affect the risk of developing COPD and etiologies, it is also associated with worsened COPD health outcomes. Effective interventions in these people are needed to decrease these disparities. Efforts that may help lessen these health inequities in low SES include 1) better surveillance targeting diagnosed and undiagnosed COPD in disadvantaged people, 2) educating the public and those involved in health care provision about the disease, 3) improving access to cost-effective and affordable health care, and 4) markedly increasing the efforts to prevent disease through smoking cessation, minimizing use and exposure to BF, and decreasing occupational exposures. COPD is considered to be one the most preventable major causes of death from a chronic disease in the world; therefore, effective interventions could have a major impact on reducing the global burden of the disease, especially in socioeconomically disadvantaged populations.

Is Chronic Obstructive Pulmonary Disease Caused by Wood Smoke a Different Phenotype or a Different Entity?

Around 40% of the world's population continue using solid fuel, including wood, for cooking or heating their homes. Chronic exposure to wood smoke is a risk factor for developing chronic obstructive pulmonary disease (COPD). In some regions of the world, this can be a more important cause of COPD than exposure to tobacco smoke from cigarettes. Significant differences between COPD associated with wood smoke (W-COPD) and that caused by smoking (S-COPD) have led some authors to suggest that W-COPD should be considered a new COPD phenotype. We present a review of the differences between W-COPD and S-COPD. On the premise that wood smoke and tobacco smoke are not the same and the physiopathological mechanisms they induce may differ, we have analyzed whether W-COPD can be considered as another COPD phenotype or a distinct nosological entity.

Clinically relevant subgroups in COPD and asthma

As knowledge of airways disease has grown, it has become apparent that neither chronic obstructive pulmonary disease (COPD) nor asthma is a simple, easily defined disease. In the past, treatment options for both diseases were limited; thus, there was less need to define subgroups. As treatment options have grown, so has our need to predict who will respond to new drugs. To date, identifying subgroups has been largely reported by detailed clinical characterisation or differences in pathobiology. These subgroups are commonly called "phenotypes"; however, the problem of defining what constitutes a phenotype, whether this should include comorbid diseases and how to handle changes over time has led to the term being used loosely. In this review, we describe subgroups of COPD and asthma patients whose clinical characteristics we believe have therapeutic or major prognostic implications specific to the lung, and whether these subgroups are constant over time. Finally, we will discuss whether the subgroups we describe are common to both asthma and COPD, and give some examples of how treatment might be tailored in patients where the subgroup is clear, but the label of asthma or COPD is not.

Chronic obstructive pulmonary disease induced by exposure to biomass smoke is associated with a Th2 cytokine production profile

Smoking and exposure to biomass smoke induce the release of pro-inflammatory mediators and the activation of T helper cells. The resulting inflammatory response contributes to the development of COPD. Clinical heterogeneity exists among COPD patients, particularly between patients with disease associated with tobacco smoking (TS-COPD) and those exposed to biomass smoke (BE-COPD). The aim of this study was to identify whether exposure to tobacco and biomass smokes promotes different Th responses that contribute to clinical variability. The study only included women. The frequency of Th17 cells in patients with TS-COPD was significantly higher than in patients with BE-COPD and healthy controls (HC). In contrast, patients with BE-COPD had higher levels of Th2 cells than TS-COPD and HC. In accordance, IL-4 serum concentration was higher in BE-COPD than in TS-COPD. Our data indicates that the different responses induced by these two irritants may underlie the clinical heterogeneity between TS- and BE-COPD patients.

FEV1 decline in patients with chronic obstructive pulmonary disease associated with biomass exposure

RATIONALE

Biomass exposure is an important risk factor for chronic obstructive pulmonary disease (COPD). However, the time-course behavior of FEV1 in subjects exposed to biomass is unknown.

OBJECTIVES

We undertook this study to determine the FEV1 rate decline in subjects exposed to biomass.

METHODS

Pulmonary function was assessed every year in a Mexican cohort of patients with COPD associated with biomass or tobacco during a 15-year follow-up period.

MEASUREMENTS AND MAIN RESULTS

The mean rate of decline was significantly lower for the biomass exposure COPD group (BE-COPD) than for the tobacco smoke COPD group (TS-COPD) (23 vs. 42 ml, respectively; P < 0.01). Of the TS-COPD group, 11% were rapid decliners, whereas only one rapid decliner was found in the BE-COPD group; 69 and 21% of smokers versus 17 and 83% of the BE-COPD group were slow decliners and sustainers, respectively. A higher FEV1 both as % predicted and milliliters was a predictive factor for decline for BE-COPD and TS-COPD, whereas reversibility to bronchodilator was a predictive factor for both groups when adjusted by FEV1% predicted and only for the TS-COPD group when adjusted by milliliters.

CONCLUSIONS

In the biomass exposure COPD group the rate of FEV1 decline is slower and shows a more homogeneous rate of decline over time in comparison with smokers. The rapid rate of FEV1 decline is a rare feature of biomass-induced airflow limitation.

Profiles of chronic obstructive lung disease: characteristics of stable chronic obstructive lung disease in different parts of Asia

PURPOSE OF REVIEW

This review discusses the recent Asian chronic obstructive lung disease (COPD) studies that characterize stable COPD, to understand its peculiarities.

RECENT FINDINGS

Asian research has improved our understanding of COPD. Household air pollution (HAP) is as important as smoking. Smoking in Asia is varied, and noncigarette smoking exposure remains under-investigated. Prevalence studies are often questionnaire based. Spirometry-based prevalence needs study. Burden of obstructive lung disease studies are getting published. Female COPD in Asia is predominantly HAP induced. The patients are underweight, milder 'Global Initiative for Obstructive Lung Disease- class' and have compromised health-related quality of life often with depression and anxiety, but other comorbidities do occur and are getting defined.Nonsmokers' COPD is often associated with small airway thickening, less emphysema, but considerable morbidity. Asian COPD may have an eosinophilic component, but its significance is unknown. There is genetic predisposition among some Asians to COPD, and among some patients to lung cancer. The emerging pandemic of lifestyle diseases demands that metabolic and cardiovascular comorbidities in COPD need investigation.

SUMMARY

COPD in Asia is increasing and burdensome. It is affecting both sexes; is caused by HAP as much as smoking; causes poor quality of life and intense psychological burden; and is associated with unique patho-physiology, which will require research and action.

Clinical Characteristics of Patients With Biomass Smoke-Associated COPD and Chronic Bronchitis, 2004-2014

Individuals with chronic obstructive pulmonary disease (COPD) associated with biomass smoke inhalation tend to be women born in rural areas with lifelong exposure to open fires while cooking, but can also include persons with prenatal and childhood exposure. Compared with individuals with COPD due to tobacco smoking, individuals exposed to biomass smoke uncommonly have severe airflow obstruction, low diffusing capacity of the lung for carbon monoxide (DLCO) or emphysema in high-resolution computed tomography (HRCT) but cough, phlegm and airway thickening and air trapping are very common. Autopsies of patients with COPD from biomass smoke exposure show increased pulmonary artery small vessel intimal thickening which may explain pulmonary hypertension, in addition to emphysema and airway disease. Research on similarities and differences in lung damage produced by exposure to biomass fuel smoke while cooking vs. smoking tobacco may provide new insights on COPD. As a public health problem, COPD caused by inhalation of smoke from burning solid fuel is as relevant as COPD caused by smoking tobacco but mainly affects women and children from disadvantaged areas and countries and requires an organized effort for its control. Improved vented biomass stoves are currently the most feasible intervention, but even more efficient stoves are necessary to reduce the biomass smoke exposure and reduce incidence of COPD among this population.

Tomographic and functional findings in severe COPD: comparison between the wood smoke-related and smoking-related disease

OBJECTIVE

Wood smoke exposure is a risk factor for COPD. For a given degree of airway obstruction, the reduction in DLCO is smaller in individuals with wood smoke-related COPD than in those with smoking-related COPD, suggesting that there is less emphysema in the former. The objective of this study was to compare HRCT findings between women with wood smoke-related COPD and women with smoking-related COPD.

METHODS

Twenty-two women with severe COPD (FEV₁/FVC ratio < 70% and FEV₁ < 50%) were divided into two groups: those with wood smoke-related COPD (n = 12) and those with smoking-related COPD (n = 10). The two groups were compared regarding emphysema scores and airway involvement (as determined by HRCT); and functional abnormalities-spirometry results, DLCO, alveolar volume (VA), the DLCO/VA ratio, lung volumes, and specific airway resistance (sRaw).

RESULTS

There were no significant differences between the two groups in terms of FEV₁, sRaw, or lung hyperinflation. Decreases in DLCO and in the DLCO/VA ratio were greater in the smoking-related COPD group subjects, who also had higher emphysema scores, in comparison with the wood smoke-related COPD group subjects. In the wood smoke-related COPD group, HRCT scans showed no significant emphysema, the main findings being peribronchial thickening, bronchial dilation, and subsegmental atelectasis.

CONCLUSIONS

Female patients with severe wood smoke-related COPD do not appear to develop emphysema, although they do show severe airway involvement. The reduction in DLCO and VA, with a normal DLCO/VA ratio, is probably due to severe bronchial obstruction and incomplete mixing of inspired gas during the determination of single-breath DLCO.

Correlates of COPD and chronic bronchitis in nonsmokers: data from a cross-sectional study

Purpose

Our objective was to assess the prevalence of chronic bronchitis and chronic obstructive pulmonary disease (COPD) and their correlates among a Lebanese nonsmoker group.

Material and methods

A cross-sectional study was conducted between October 2009 and September 2010, using a multistage cluster sample throughout Lebanon including Lebanese residents aged 40 years and above with no exclusion criteria. Pre- and postbronchodilator spirometry measurements were performed and carbon monoxide level was measured in exhaled air. COPD was defined and classified according to the Global Initiative for Chronic Obstructive Lung Disease guidelines or according to the lower limit of normal (forced expiratory volume in 1 second/forced vital capacity postbronchodilator < 5th percentile of the healthy population having the same age and sex). Chronic bronchitis was defined by the declaration of morning cough and expectorations for more than 3 months a year over more than 2 years in individuals with normal spirometry.

Results

Out of 2201 individuals, 732 were never-smokers: 25 (3.4%) of them had COPD, and 86 (11.75%) fulfilled the definition of chronic bronchitis. Correlates of COPD included a childhood respiratory disease, house heated by diesel, and older age. On the other hand, correlates of chronic bronchitis included childhood respiratory diseases, living in southern Lebanon versus other regions, heating home by gas, older age, number of smokers at work, and lower height.

Conclusion

A substantial percentage of the nonsmoking population may exhibit chronic bronchitis or COPD. The significant correlates mentioned above should be taken into consideration in order to reduce the risk of developing such chronic and debilitating respiratory diseases.